Normally, after an engine has run for a period of time, the exhaust pipe on the engine accumulates carbon ashes, dirt substances, and water or oil on the inner surface. The dirt accumulated in the exhaust pipe may increase gradually so that the passage for the exhaust becomes narrower and the discharge rate of the exhaust becomes worse, exhaust is not discharged smoothly, unfavorable phenomena occur, such as the temperature of the engine cylinder rises above the acceptable range, part of the exhaust remains in the engine cylinder, etc. The rise of the temperature in the engine cylinder may unfavorably affect the fuel burning process during the combustion stroke. When exhaust remains in the engine cylinder, insufficient fuel-air mixture results or insufficient pure air capable of entering the engine cylinder is available during the intake stroke. Even more serious, these phenomena will lead to undesirable drawbacks such as low engine running efficiency, deficient horsepower, and harmful exhausts are formed toxic to health. Therefore, it is quite important to keep the inner wall of an exhaust pipe clean and also to clean exhaust pipes for engine maintenance.
Nevertheless, up to the present, there has not been a proper and handy cleaning tool available for cleaning the inner wall of an exhaust pipe so that keeping the exhaust pipe clean is a problem for the maintenance personnel. Frequently it is necessry to replace the exhaust pipe instead of cleaning the exhaust pipe.